Small-bore tubing, and method and apparatus for the making of same



Nav.' 13, 1928. 1,691,134

H. scHLAlcH SMALL BORE TUB-ING AND METHOD AND APPARATUS FOR THE MAKING OF SAME Filed April 10.1918

Patented Nev. 13, 1928.

UNITED STATES HERMAN S'CHLAICH, 0F BROOKLYN, NEW YORK..

Application filed April 10, 1918. Serial No. 227,754.

This invention relates to the manufacture of small bore tubing and more especially to a shape`or construction of tubing ofi substantially capillary bore adaptedA for use in thermometers of the distance type or for other similarpurposes where a fluid filled ltransmission@tube' maybe employed.

The invention comprises also a novel 'method oi' an 5 apparatus for manufacturing such tubing. Another feature of the invention relatesto the construction oit tubing of the characterset forth provided with a. casing.

The' objects'of the invention include the production of a novel form of tubing so shaped as tohave a bore smaller than that of the smallest tubingwhich is now com'- mercially'fmanufactured by the' usual tube producing methods; the producing of tubingy of this character rapidly and cheaply, and the encasement of such tubing ina protective and heat insulating sleeve 1n a simple and economical manner. Anothereobject of the invention is the provision of a tube of such shape that it is not easily crushed or flattened out so as to entirelyv close the opening thereof. The nature and specific objects of the' inventionwill be clear from the following description of one embodiment of the invention illustrative of the principle thereof. j i

In the accompanying drawings which form a part of this specication, Figure l is a side elevation of an apparatus which may be employed in the production of the novel form of tubing. Figure 2 -is afront elevation ot the apparatus shown in Figure 1. Figure 3 is a detail sectional view showing a clamp for holding the encasing sleeve and showing how the reshaped tubing can be'v forced into this sleeve or casing. Figure 4 is a cross section on `enlarged scale showing the reshaped tubing enclosed within the 'sleeve or casing. Figure 5 .isal diagrammatic cross sectional view of the Teshaped tubing showing how it maybe deformed without entirely closing the opening there!v through. Figure 61s a diagrammatm viewv illustrating the iiovel tubing as employed -in a temperature indicating instrument for the internal combustion engine of an automobile,v

aeroplane or the like. Figure 7 is a diagrammatic view illustrating a modiied form of the tubing and of rolls for producing the same.

My .invention isconcerned mainly withA tubing of very small bore` such as is em- `the latter. will give an usual radiator 27.

ployed in the example of tlie"app1ication of the invention illustrated in Figure 6, where ycolumn of fluid in the tube 3, causes an increase ordecrease of. the pressure in the BourdonA spring or other pressure responsve element in the gage 22 so that indication of temperature changes` at the bulb. In the particular example illustrated the bulb 2S ythe 'tubing constitutes the connecting or 1s vshown as located in the return pipe 26 of l the cooling system of an internal-combustion engine .as setforth in the patent to Boyce No. 1,206,783. The cooling water circulates through the jacket 25 around the cylinders 24 .and through the return pipe 26 to the The bulb 28 is thus so located as to'be influenced by the cooling Water after it has reached its highest temperature. The instrument 22 is located at some distance from the bulb`28 and in a convient position for observation by the operator, usually upon the dash board 23. It is thesobject of an instrument of this character to give an accurate indication of temperature changes at the bulb or temperature .responsive element but a source of error exists in the column of fluid contained within the tube 3. ThisY tube is usually of considerable length and is subjected to temperature conditions which may vary greatly and which are usually uite different from the temperatures to .which the bulb 28 is subjected. The column of fluid in the tube will therefore expander contract in accordance with the variation in these external conditions and Wholly independently oit the temperature of the bulb. If the volume of fluid in the tube 3 is suflicientlysmall as compared with the volume of lluid in the` bulb, the error produced by the expansion or contraction of the fluid in the' tube willbe so small as, to be negligible but if the volume of Afluid in the tube is considerable the error from'this source may be so great as to render the instrumentv virtually useless. The importance of reducing the capacity of the tube is therefore at once apparent and the present invention is directed primarily toion I 5 the invention therefore also preferably pro wardseliecting suc'lireduction. The errors dueto expansionl or contraction of the fluid in` the tube may also be reduced by reducing the temperature variations of the tube and vides forthe encasing of the tube in a temperature insulating shell orsleeve which acts lasa mechanical protection as wellV for the tube.

Vhile it hasbeen knownthat it was very desirable to utilize in temperature indicating instruments of the character referred to, a tube having a small bore, it has not been practical by ordinary commercial processes 15- to produce such tubing having an internal diameter` of less than approximately fifteen -vthousandths of an inch. The employment of tubing having a bore of this vor' larger diameter introduces great errors into an 2U instru-ment,l and itv has therefore been attempted to reduce the volume'of the tubingy Y by introducing a wire into the same, partly 'filling up the bore. y'The use of such a filling '.wire is, however, not satisfactory as it must eitherbe so much smaller than the internal diameter of the tube as not to accomplish the desired purposes or if it is'attempted to utilize a wire of sullicient diameter to almost'ill the bore it'so difficult of insertion 3u. into the-tubing, as to be commercially impracticable I accomplish the ldesired result of-reducing the -voliune of the tubing without the introduction ofany ller thereinto.

but merely by reshaping thetubing so as 3f, to greatly diminish the cross section of the bore thereof. In accordance with my invention I am able to produce vreshaped tubing having a volume much less thanthat of the smallest commercial drawn tubing and much less even than the volume of such tubing when provided withsa filling wire'. I am also able -to produce such reshaped tubing in any length and in an exceedingly rapid and economical manner. A

instrumentalities maybe employed but preferably I make use of mechanism comprising a pair of rolls 1 mounted so that their faces rotate in contact with each other; and in each roll I provide a groove 2. These grooves are approximately V-shaped but have their sides slightly'convex; that is to say, these grooves will `be in cross section somewhat like a Vif the arms of this V are curved away from* each othertoward their outer ends. The 'grooves may be described as, cusp-shaped.

Whenv the rolls'are in operative position the groove of one will register 'with the groove of the other, as indicated in Figure l; and the space enclosed bythese grooves at the point where the rolls touch each other will have the form of a four-sided figure with its sidesconcave, as Figiirel illustrates. I do not.l however, wishto limited to any par- 5 ticular cross sectional shape in connectionl Iny practicing my invention anysuitablev mariee with the grooves 2, as.I may wish to vary the configuration of these .grooves under different conditions.

In operation, apiece of tubing, such for instance as ordinary vsmall boredrawn cop per tubing which is round on the outside, and has a round bore therethrough, is passed between these rolls, and is reshaped by them.`

Such a piece of tubing is indicated at .3 in Figure 2; vI'Vhen it passes between the rolls l vand through the grooves 2, these rolls compress, bend or squeeze the material forming the tubing towards the center 4or longitu- .dinal axis of the same; this compressing taking place as the`tubing passes through the rolls along successive portions of length of the tubing; and'preferably around the v'entire circumference. In consequence the tubing is insha-pcd., in lcross section, as shown at the right of Figure 2, also in Figures 3 and 4.

In the operation of reshaping, certain portions of the tubing are squeezed inward and made concave, as indicated at in 'Figure 4, and` these concave o r reentrantportions will be separated from oneanother by longitudinallyextending Yrib-like projections 6. Both the portions 5 and the projections 6 will run along the tubingfrom one end to the other, making the tubing corrugated in efect'when the. operation of the reshaping is completed. Furthermore, the bore 7- through the tubing, instead of continuing to be round. will be inv cross section somewhat like the form which Figures l and 4 present; and the cross-'sectional area of this bore will be considerably less than the cross-sectional lUil area of the bore befoie the tubing is'worked 'in the manner described. I find it possible to take a piece of tubing of very small size,

' and by ypassing it between the rolls l, to {reduce the-area of the bore to a small fraction of .its original area, and thus greatly diminish the quantity of`the fluid which is necessary to vfill the tubing.

The mechanism shown in Figures 1 and 2` comprises a shaft 8 on which the upper roll 1 1s ixed,.ogether with a support such as IUS Ilu

a journal 9, on which the lower roll 1 may.

trated arrangement in which the part 9 is fixed; sothat I may mount thereon a suitable member 10 which carries at one side of the rolls a guide 11 having an opening 12 in line with the grooves 2. On the opposite side of these rolls is a support 13 which' be mounted to turn idly..v If the shaft 8 A i vsecures the end of a piece of tubing 18 of greater bore than the outside .diameter of the tubing 3; so that the tubing 3,` after being reshaped and delivered by the rolls 1,

vin proper position on the part 9 with reference to the rolls 1.

As shown in Figure 3, the support4 13 will have`an aperture 16 which is enlarged to provide a shoulder 17. The piece of tubing which is to make the sleeve or jacket for the tubing '3"is inserted into the opening. in the support until its end abuts against the shoulder 17. Around the tubing 18 adjacent this end is a nut 19 having a milled rim 20 to enable it to be manipulated. This nut has screw threaded engagement with the support/13, audits end is tapered or conical to vk. engage aconical Walled section 21 of. the

aperture through the support beyond the shoulder 17 in the direction of travel of the tubing 3. I slot this nut in several places around the circumference thereof, from the conical end towards the milled rim 20. Hence, when the nut 19 is screwed into the support as far as it VWill go, the Iconical Wall 21 will compress the inner end' of the nut; thereby causing it to clamp the end of the tubing 18, andthus hold the tubing 18- in p place.

By this arrangement of .parts I not only am enabled to reshape a piece of tubing having albore of capillary dimensions; but also, in the same operation, to insert it into the sleeve 18, even though a considerable length of tubing is required' to be reshaped and enclosed in a sleeve in this Way. The tubing 3 goes into the tubing 18 easily, even though one or both pieces of tubing may be curved or bent; but the liability of any bends occurring in the tubing 3 of course is greatly lessened by the .fact that the operation of the rolls 1, beside reshaping the tubing 3 also tends to smooth the same out and eliminate bends. Furthermore, by reshaping the tubing 3 in such a Way as to 'provide the riblike projections 6, the tubing 3 is reinforced longitudinally and becomes stiffer and more rigid and'thus can be pushed intol the sleeve 18 so much more readily and with less liability of being obstructed.

By the process set forth above I am not only enabled to reduce the cross-sectional area 7 of the Whole of the tubing 3, and thus reduce the amount of liquid required. to fill it, but I am also enabled to enclose the tub- This follows because the star shaped tubing 3 will contact v'vith the inner surface of the sleeve only along one or fnore of the ribs or ridges 6, thus yielding substantiallyA line contact'with the minimum area for heat transference. Furthermore the ridges support the body of the tube substantially in the middle of the sleeve or casing thus providing considerable air spaces upon all sides of the tube. Y

Figure 5 shows the capacity of my novel form of tubing for considerable distortion ,or crushingwithout completely closing the rl`he tubing may be opening therethrough. crushed to such an extent that -tWo of the reentrant sides are brought into contact While still leaving a sutlicient opening to permit the fluid to move through the tube.

In'Fig'ure 7 I have shown a modified-form -i of the tubing which is depressed from three l directions so asto produce a tube of substantially triangular configuration as shown at 30. This form may be produced by the use of'threev rollsll mounted on axes' 32' arranged at angles of 60"v to one another.

readily suggest themselves.

lVhile Iv have described and illustrated in detail certaiupreferred forms of my invention and a method and apparatusby which my novel tubing maybe produced it is to be understood that `the invention is capable of a Wide range of modification, that variations may be made in the shape of the tubing,

and that the tubingmay be produced by any suitable method and with the use of appayratus other than that described. I' do not therefore desire Lto `be limited in the applilul) cation of my invention but intend to cover the faces ofthese rolls may be flat if desired.

I may also use an arrangement of more than 3 rollers With flator convex faces to Work a piece of tubing in order to reshape it and reduce the capacity of the bore, as will be readily understood.

I may also under some conditions give the groove 2 in the rolls 1 the crosssectional shape of a' semi-circlc. With such a construction the capillary tubing will remain tubular after being Worked by being passed between the rolls 1, through the grooves 2. In this case it Will simply be compressed and the 'capacity of the bore reduced Without alteration.

the cross-sectional shape undergoing any lll) un Other possible formations of the tubing will The term capillary tubing as use d in the present specificationan'd claims is intended to define tubing of the smallest capacities, in which thel bore is of hair-like dimensions. Moreover, in the distance type instrumentfartin Which'the present invenl' tion finds its special field of applicability,

theterm capillary orfcapillary tube has an accepted meaning as designating the pressure transmitting tubing, connecting 'the bulb of the' instrument' with the instrument head 0r indicating' part proper which latter usually 'consistsof a' Bourdon spring which C .is .so shaped as to'change its form in re- ,sponseto 'changes in internalpressure and which therefore isv necessarily .of much greater than capillary dimensions as that term is herein employed.

Having described my invention what-I believe to be new and`des1re to Tsecure 'and protect, is z w -1. Corrugated capillary tubing. 2. Capillary metallic tubing for t ermometers and' thelile having its wall formed of' three or more longitudinally extending inwardly curved sections lunited at their adjoining edges.

3.*As an article of manufacture, tubingA having corrugations in its wall to provide longitudinally extending, -rib-like, projec`v tions lonpits exterior, and 'meansfor thermally "insulating, said tubing, said means comprising a sleeve enclosing said tubing.

4. As an article of manufacture, tubing having longitudina-l reentrant portions s epara-ted from one another by longitudinally extending rib-like projections, and meansfor `insulating said, tubing against external variations of temperature, said 4'means comprising a sleeve enclosing said tubing, the tubing making -contactwith the sleeve along said rib-like projections only.

5. The method of reducing thegvolume of capillary l.tubing-which consists in depressing a longitudina'lgroove therein.

. 6. The method of reducing the volume of .capillary tubing which consists in deforming the' tubing by forces, applied tio the tubing yfrom more than two directions' transverse to the axis vof the tubing.

7. The method of deforming capillary tubing which consists-in rolling three or more longitudinal depressionsin the tubing, so as to reduce the volume contained Within the tubing.

8. The method of encased tubing Whichconsists' in holding the casing stationaryan'd feeding finished tubingrbetween rollsfvvhich deform it in such a wa as to reduce its volumetricconitentand orce it'into said'casingty `9.The niethodof producing small bore encased tubingwhich consists in supporting an end of the casing in xed position adf .ter into said casing,

producing small i bore I jacent to set `of rolls and feeding finished tubing between said rolls and from the latsaid rolls compressing the tubing to reduce its volumetric content and forcing'the same into said casing.

10. The method of working tubing which consists in reshaping a pieceof tubing by compressing the tubing about its circumfei-,

ence along successive portions of the length of the tubing, to provide rib-like proJect-ions .with reentrant portions between the piojections, andthen feeding said tubing into va sleeve or' casing.

- 11.. The combination of aupairof iolls having grooves forreshaping a piece of tubing, a guide at oneside of the rolls, a support on the other side of the rolls, and

means comprising aslotted nut and a meniber having a conical bearing surface for said nut for securing to the support the end of' a largerpiece of tubing to receive`the first tubing after the rolls deliver the same.

12. Capillary tubing deformedto reduce the volumetric capacity of the bore thereof.

13. The method of insulating tubing againstlexternal temperature changes, which consist-s in deforming the" same so as to provide 'longitudinal rib-like lprojections thereon 4and enclosing the tubing by a sleeve such that the same can make Contact only'` with4 said projections.

1 4. The method o f 'rendeiing tubingsuitable'l for transmission of variations of kthe volume and pressure of a `fluid, which consists in deforming the l tubing to reduce the capacity of `its' bore, and enclosing the tubing in a sleeve to thermally insulate the same.

15.4 The method of renderingtubing suit `able for accurate transmission of variations 'of volumes andvpressures of fluids, which consists in corrugating the tubing to lreduce the volumetric capacity of its bore and enclosing it in a sleeve arranged to contact only with the outer edges of the said cor.

about the circumference, whereby `the said tubing is-caused to have a cross sectional area considerably below that of -the tubing in' its original state. f.

In testimony whereof, I have signed my name tothis specification this 16th day of March, 1918. l

. HERMAN lSCHLAIGH.

intemperature or 

